Ocean response to hurricane forcing.

Abstract

The current meter records collected at three sites in the Gulf of Mexico during the passage of Hurricane Frederic are analyzed to determine the storm-induced flow at various ocean depths, determine the associated energy increase and decay, and compare these observations to similar results from a numerical model. The records at the two deeper sites are rather unique because they are within 100 km of the hurricane track. Pre-storm conditions are controlled by topography, and as the storm passes there is an abrupt change in the direction of flow and initiation of a strong inertial response at all levels of the two deeper sites. After this initial surge, the residual flow tends toward the pre-storm direction. The horizontal kinetic energy associated with inertial motion is calculated. The energy increase and decay is shown to vary with depth. An embedded mixed-layer ocean circulation model is forced with an idealized storm translating at the same speed as Frederic. The abrupt response and strong inertial component predicted by the model is qualitatively similar to the observations.